Damaged Mallory HEI – You Break It, You Fix It!

Restoring Power To A Damaged Mallory HEI Is Easier Than You May Think

Racers are famous for being able to break just about anything. And not surprisingly, we’re no different from them. A perfect case in point is our dyno test mule engine. We recently used it to test different rocker arm setups and destroyed two of the six rocker sets we tested. What we didn’t mention in that story (“Design Matters,” Mar. ’07), however, is that we also managed to hurt our Mallory HEI ignition.

It wasn’t deliberate. The Mallory distributor had served its duty well on previous dyno tests, but this time we had a wiring mishap while hooking the engine up to the dyno. Somehow, a ground wire was hooked to the lead for the tach, and before long a faint wisp of smoke from underneath the rotor cap indicated that something was amiss. Names will not be revealed here because it was an honest mistake that anyone could make (although we are reserving the right to blackmail the guilty party later). Thankfully, a race-bred ignition like our Mallory is easily rebuilt.

Since an HEI uses an internal coil, it is easy to wire and a foul-up such as ours is quite rare. However, regular wear-and-tear from racing is an issue. Being the inventive lot we are, there are a number of additional ways racers can damage equipment. In the interest of getting our ignition up and running again, we gave the folks at Mallory a call to inquire about rebuilding it. They sent us the components to complete the task ourselves, which was surprisingly easy. Our replacement components included a new performance coil (PN 29215), which is effective up to 7,000 rpm, a rotor (PN 362), and a Hyfire HEI module (PN 699). So, if you burn a coil, chip the rotor, or create any other damage, consider rebuilding your own HEI distributor. Mallory’s high-power module and coil are also compatible with stock distributors as power upgrades. If your class requires stock components, this is a good way to get rid of a high-speed miss (the curse of stock HEI ignitions) while keeping that stock look.

Easy Fixes Having an ignition problem? The following is a list of the most common technical questions asked of Mallory’s Mike Golding along with practical solutions for each.

Q I put a new high-output ignition system in my car and it started missing. I thought something was wrong with the ignition, so I exchanged it for another one. It is still doing the same thing. What’s going on?

A The problem isn’t the ignition box. It is somewhere else, and that somewhere is often the spark plug wires. Here’s what is happening. Your new high-output ignition delivers several times more current to the spark plugs, and the wires probably cannot contain it. So they leak energy or short out to ground. Resistor plugs can contribute to the problem as well as corroded terminals or ill-fitting boots on the wires.

It’s like the hose you use to wash your car. When the nozzle is open and there is very little pressure in the hose, the nozzle only leaks a little at the connection between the hose and the nozzle. When you close the nozzle and the hose builds up pressure, water sprays from that bad connection and soaks you.

Q I just put a new cap on my distributor and the car started to miss. I took off the cap and the carbon tip inside the cap was chipped. Was it a bad cap?

A The cap was probably just fine. What went wrong was the installation. It is very important to lower the cap straight down onto the distributor. Otherwise, the tip of the rotor catches the edge of the carbon and it chips.

Q Why do the catalogs always tell you what coil to run with a particular ignition, especially with a CD ignition? Are they just trying to sell more parts?

A Especially in the case of a CD ignition box, the coil is an integral part of the ignition system. The box and coil are designed to work as a team. If things are not compatible, you not only lose performance, you also generate excess heat either in the coil or in the ignition box.

Q Is the manner in which I mount my new coil important?

A Yes, for a couple of reasons. First of all, some coils are filled with special oil that keeps them cool inside. They are designed to have a little air space at the top, away from the heat-generating windings. Mounting them the wrong way can cause them to overheat internally.

Here’s a helpful hint. Try to mount your coil in such a manner that the coil wire will only need to be 18 inches or less. Also, try to keep it away from as much heat as possible and where there is some airflow.

Q I just installed a new ignition box and something doesn’t feel quite right. I wired in my new one the same way I wired the other brand I had. What gives?

A Whenever you add a new ignition box, you need to recheck the ignition timing. It often changes a couple of degrees, even if you are just going from one box to another.

Q I noticed some HEI distributors have two wires to hook up and others have three. Why the difference?

A Some distributors use a separate ground wire while others count on grounding through the housing. A separate ground wire is cheap insurance and highly recommended. Most distributors have a gasket between the housing and the engine, and the housing has O-rings. That leaves only the distributor/oil pump drive, which is coated in oil, and the distributor clamp to supply the ground.

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